All Men Are Created Equal

One hundred sixty-nine years ago, on July 4, 1776, a group of men drew up the document which is known today as the Declaration of Independence. These men did not meet with that end in mind. Their primary purpose in having that historical meeting was to evolve a plan whereby they might, in some way, overthrow the severe restrictions they were suffering at the hands of the British Crown. Foremost in the minds of them all was a feeling that had motivated the colonization of this hemisphere; the feeling that had instilled within them a vivid will to perpetuate a free world for all men, a world founded upon the proposition that, All men are created equal

Meander belt delineation: Developing a predictive model for meander belt width

The delineation of a meander belt has been recognized in Ontario through land use planning policies as a primary tool for determining the extent a river or stream requires for natural meandering tendencies; thus, providing input to channel restoration projects, development constraints or limits, and regulated areas for species-at-risk. Current delineation procedures utilize site-specific historical migration assessments, or published empirical equations to predict meander belt width. In the case of altered, low order watercourses in southern Ontario, the meander belt width dimension is usually assessed by the application of empirical relations, as the available historic record often lacks the information necessary to conduct meander morphology and migration assessments. There is limited research concerned with the variables controlling meander belt development, and on the precision and reliability of the measurement of belt width. Drawing on a sample population of river reaches in the Credit River watershed, this research project evaluates the current standards of practice for meander belt delineation in southern Ontario, focusing on empirical equations to determine whether the width of the meander belt can be reliably predicted from hydro-geomorphic variables. Results suggest meander belt width is scaled to drainage area, discharge, and bankfull channel width. These results differ from equations commonly used in Ontario assessments suggesting further need for model testing and assessment of the reliability of meander belt width as a planning tool

Investigating the Effects of Radiation on Phosphonium-Based Ionic Liquids

This thesis presents work on the understanding of the effects of ionizing radiation on phosphonium-based ionic liquids (ILs). The capability of ILs to dissolve a wide range of molecules, and the potential of ILs to be highly resilient in energy-intensive environments makes them particularly promising media for the separation and sequestration of metal ion contaminants from radioactive waste effluents in nuclear fuel cycles. For this application, a water/IL system will be exposed to a continuous stream of ionizing radiation. The radiation environment will strongly influence the chemical state of the water phase in the system and the chemical parameters affecting the separation efficiency of the system. This work examines irradiation of gas/IL and water/IL biphasic systems containing phosphonium-based ionic liquids. When exposed to ionizing radiation, ionic liquids undergo radiolysis, resulting in the formation of ionic liquid excited species and radiolytic fragments. As well, when exposed to ionizing radiation, water decomposes into a range of reducing (•eaq−, •O2−, •H) and oxidizing (O2, •OH, HO2•, H2O2) species. To develop a better understanding of the biphasic water/IL systems when exposed to radiation, small samples of the biphasic systems were exposed to continuous radiation in a gamma-cell for periods of time up to several days. A number of surface, spectroscopic, and electrochemical techniques were employed to follow the evolution of the systems. This combination of analytical techniques allowed for the study of changes in the ionic liquid phase, the water phase, and the gas phase in the systems. Results indicate that even long-term continuous doses of gamma-radiation induce a negligible chemical change in phosphonium-based ILs when they are in contact with a gas phase. In the case of the water/IL system, ion transfer occurs across the water/IL interface, even with the most immiscible phosphonium-based ILs. Irradiation produces surfactants that can accumulate at the interface and accelerate mixing of the IL and water phases by emulsification and the formation of micelles. Despite the micelle formation and emulsification, studies concluded that the phosphonium-based ILs studied undergo very little radiolytic degradation in steady-state gamma-radiation fields

Dione's thermal inertia and bolometric Bond albedo derived from Cassini/CIRS observations of solar eclipse ingress

On 2010 May 18 Cassini's Composite Infrared Spectrometer (CIRS) observed Dione's leading hemisphere as its surface went into solar eclipse. Surface temperatures derived from each of CIRS' focal plane 3 (FP3, 600−1100 cm−1) show a rapid decrease in Dione's surface temperature upon eclipse ingress. This change was compared to the model surface emission to constrain bolometric Bond albedo and thermal inertia. Seven FP3 detectors were able to constrain the observed surface's thermophysical properties. The bolometric Bond albedo derived from these detectors are consistent with one another (0.54 ± 0.05 to 0.62 ± 0.03) and that of diurnal studies (e.g., 0.49 ± 0.11, Howett et al. 2014). This indicates that Dione's albedo is uniform to within the uncertainties across the observed region of its leading hemisphere. The derived thermal inertias are consistent across detectors, 9 ± 4 J m−2 K−1 s−1/2 (MKS) to 16 ± 8 MKS, and with previous diurnal studies (e.g., 8 to 12 MKS, Howett et al. 2014). The skin depth probed by the eclipse thermal wave is ∼0.6–1 mm, which is much shallower than that probed by diurnal cycles (∼50 mm). Thus, the agreement in thermal inertia between the eclipse and diurnal studies indicates that Dione's subsurface structure is uniform from submillimeter to subcentimeter depths. This is different from the Jovian system, where eclipse-derived thermal inertias are much lower than those derived from diurnal studies. The cause of this difference is not known, but one possibility is that the E-ring grains that bombard Dione's leading hemisphere overturn it, causing uniformity to centimeter depths

The function and structure of the entorhinal cortex in mild cognitive impairment

The function and structure of the entorhinal cortex in mild cognitive impairment Background: The entorhinal cortex (EC) is the first brain region to exhibit neurodegeneration in Alzheimer’s disease (AD). As such, tests of EC function may help aid detection of the disease in its earliest stages. Animal and human studies indicate that the posteromedial (pmEC) and anterolateral (alEC) subdivisions of the EC are involved respectively in navigation and object-location memory. The advent of immersive VR (iVR) technology provides an opportunity to determine whether tests of pmEC and alEC function has value in the detection of AD prior to dementia onset. Aim: To test the hypotheses that measures of pmEC and alEC function and structure differentiate i) patients with mild cognitive impairment (MCI) from age-matched healthy controls and ii) MCI patients at high and low risk of developing AD dementia. Methodology: Participants underwent testing of EC function using novel iVR paradigms of path integration and object-location memory. Total EC, pm-EC and al-EC volumes were segmented from high resolution MRI. A proportion of MCI patients underwent CSF testing for AD biomarkers to separate into biomarker-positive and negative groups (MCI+ and MCI-). The ability of the VR tests to classify pre-dementia AD (i.e. MCI+ patients) was compared with that of a battery of comparator cognitive tests used in current clinical and research practice. 8 Results: Performance on the path integration task was not only impaired in MCI but importantly differentiated MCI+ from MCI- with greater classification accuracy than comparator cognitive tasks. Task performance correlated with pm-EC volume. For the object-location task MCI patients demonstrated larger distance errors than controls, with performance associated with both anterolateral EC volume and total hippocampal volume. However, no difference between MCI+ and MCI- was observed. Conclusion This work demonstrates that iVR-based testing of EC function may improve diagnosis of early AD above and beyond current cognitive tests. The basis of such tests on single cell physiology and their comparability with behavioural tasks used in animal models of disease, confers additional advantages for translational research aimed at understanding the mechanisms linking pathological spread, disruption of cell physiology and behavioural alterations in early AD.MRC Sackler fund

Induction of productive human papillomavirus type 11 life cycle in epithelial cells grown in organotypic raft cultures

AbstractThe study of the human papillomavirus (HPV) life cycle was hampered for more than 50 years by the lack of a conventional cell culture system for propagating HPV. Considerable progress has been made in the production of several HPV types using either organotypic rafts or human epithelial xenografts in immunocompromised mice. In this study, we demonstrated episomal maintenance of HPV-11 DNA in N-Tert cells. HPV-11 episomal DNA containing cell populations grown in raft culture showed induction of the productive viral life cycle. HPV-11 DNA amplification and viral capsid antigen synthesis were detected in differentiated layers of epithelia. The viruses generated were able to infect keratinocytes in vitro, which indicate that viruses generated were infectious. The demonstration of the productive HPV-11 life cycle in raft culture from cloned HPV-11 DNA will facilitate genetic analyses of viral gene functions that was not possible using the human xenograft athymic mouse model

The behaviour of spent nuclear fuel in wet interim storage

The UK is currently transitioning from a closed nuclear fuel cycle to an open cycle. During this transition, wet interim storage of AGR spent nuclear fuel in the UK will be extended until a long term disposal facility becomes operational. The current THORP Receipt and Storage pond is to be converted into an interim storage facility. Spent fuel will be more densely packed in this pond to accommodate current and future spent nuclear fuel. There will a resulting rise in pond water temperature from 24 ◦C to between 45-60 ◦C. This necessitates further research into the long term stability of stored spent nuclear fuel. This thesis describes the corrosion behaviour of AGR fuel cladding and AGR spent fuel under conditions relevant to the lengthened storage periods. An electrochemical study of the corrosion behaviour of unirradiated and unsensitised 20/25/Nb stainless steel under alkaline spent nuclear fuel interim storage pond water conditions is presented. The results give preliminary indications that dosing pond water to a pH'11.4, with an expected chloride concentration of ∼1 ppm and hydrogen peroxide concentration of ∼1 ppm, provides corrosion protection to unstressed cladding samples at the temperatures studied, 24 ◦C (current conditions), 45 ◦C (projected future pond temperature) and 60 ◦C (predicted peak operating conditions). Analogues for fuel cladding affected by radiation induced sensitisation were developed by the National Nuclear Laboratory. For both heat treated 20/25/Nb stainless steel and heat treated 304H stainless steel, experiments provide initial evidence that for sensitised 20/25/Nb SS dosing pond water to a pH'11.4, with an expected chloride concentration of ∼1 ppm and hydrogen peroxide concentration of ∼1 ppm, will lead to the passivation of the cladding surface for pond water temperatures between 24 and 60 ◦C. However general corrosion rates are higher than those of the unsensitised counterparts and spent fuel stringers likely to be affected by RIS should be monitored more closely. In the unlikely event that the fuel cladding is perforated, the fuel itself will be exposed to pond water. Thus in order to assist in the generation of a thorough safety case, the corrosion of pure UO2 and AGR SIMFuels was studied under conditions typical of those found in interim spent fuel storage pond waters. With respect to the dissolution of spent fuel, it appears to be advantageous to dose the ponds to pH'11.4. The alkaline conditions in the pond water suppress the dissolution as UO2+ 2 which may otherwise occur. A U3O7/U4O9 oxide layer is predicted to be developing on the surface of the samples at the open circuit potentials, for the samples exposed to simulant pond water

Thermal properties of Rhea's Poles: Evidence for a Meter-Deep Unconsolidated Subsurface Layer

Cassini's Composite Infrared Spectrometer (CIRS) observed both of Rhea's polar regions during two flybys on 2013/03/09 and 2015/02/10. The results show Rhea's southern winter pole is one of the coldest places directly observed in our solar system: temperatures of 25.4+/-7.4 K and 24.7+/-6.8 K are inferred. The surface temperature of the northern summer pole is warmer: 66.6+/-0.6 K. Assuming the surface thermophysical properties of both polar regions are comparable then these temperatures can be considered a summer and winter seasonal temperature constraint for the polar region. These observations provide solar longitude coverage at 133 deg and 313 deg for the summer and winter poles respectively, with additional winter temperature constraint at 337 deg. Seasonal models with bolometric albedos of 0.70-0.74 and thermal inertias of 1-46 MKS can provide adequate fits to these temperature constraints. Both these albedo and thermal inertia values agree (within error) with those previously observed on both Rhea's leading and trailing hemispheres. Investigating the seasonal temperature change of Rhea's surface is particularly important, as the seasonal wave is sensitive to deeper surface temperatures (~10cm to m) than the more commonly reported diurnal wave (<1cm). The low thermal inertia derived here implies that Rhea's polar surfaces are highly porous even at great depths. Analysis of a CIRS 10 to 600 cm-1 stare observation, taken between 16:22:33 and 16:23:26 UT on 2013/03/09 centered on 71.7 W, 58.7 S provides the first analysis of a thermal emissivity spectrum on Rhea. The results show a flat emissivity spectrum with negligible emissivity features. A few possible explanations exist for this flat emissivity spectrum, but the most likely for Rhea is that the surface is both highly porous and composed of small particles (less than approximately 50 um)